Scoring system



July 2l, 1953 ww. woon, .JR

SCORING SYSTEM Filed Aug. 27, 1951 Patented` July 2 1, 1953 scoRING SYSTEM Y William W- Wood, Jr., Fentonrll.;Y.J assigner .to the United States of America as ,rllresentefd by the Secretary of the Air Force Application August 27, 19511, Serial No. 243.826 l 3 claims. (01.161.915)

This invention concerns Scoring systems and more particularly pertains to a scoring system indicating departures from prescribed limits.

In the past, direct observation and accounting have been used in making a record of departures from prescribed limits.

Objects of the present invention are to pro.- vide means for timing and scoring departures from prescribed limits with accuracy and speed and with a minimum of apparatus.

An operative embodiment of the present invention is illustrated in the single gure of the accompanying drawing showing a schematic circuit of a scoring system embodying the present invention as applied to an aircraft operation trainer shown in phantom outline.

One method for teaching an aircraft student pilot how to fly is for him to occupy atrainer I shown in dotted outline in the accompanying drawing and for him to operate the aircraft controls in response to instructions received through head phones. The accuracy of his operation of the controls on the aircraft within prescribed limits indicates his proficiency as a student. A bank indicator 2 within the trainer I represents a device to be operated by the student pilot Within prescribed limits. `A mechanical coupling 3 leads from the bank -indicator 2 to outside of the trainer I for indicating and making a record of the performance of the student pilot.

The circuit shown in theV accompanying drawing as embodying an'illustrative example of the present invention comprises a Wheatstone bridge consisting of resistors I and II and I2 to which an alternating current source applies its output in parallel. The mechanical coupling 3 from the bank indicator 2 is attached to a tap I3 on a variable potentiometer resistor I0 such that the tap I3 is moved with the operation of the bank indicator 2 by the student pilot lwithin the trainer I. A tap I4 on the resistor I I is set at a low permissible limitabove which the student pilot with! in the trainer I is to operate his bank indicator 2. A tap I5 on the potentiometer resistor I2 is set at a high permissible limit below which the student pilot Within the trainer I is to operate his bank indicator 2 The described potentiometersY I0, II and l2 with their variable contacts and lpower source will be referred to thereinafter as a sensing bridge circuit. The potentiometers in the sensing bridge circuit are high precision potentiometers.

The sensing bridge circuit passes its output to ak pair of channel input transformers and ylil. The input transformer 20 leads to a high` 2 limit channel and the inout transformer 29 leads te a lQW limit Channel, The high and low llimit channels are Ysubstantiallv duplicates of each other and consequently corresponding Components bearcorresponding reference numerals, with the reference numerals unprmed in the high limit channel and primed in the low limit channel. Since the high and. low limit channels are very muohalike in -both components and functions, a .description 'of the construction and operation vof the high limit channel will be adequate to explain both channels.

Within the vsensing bridge Circuit the variable potentiometer l0 witnits tan I3 and the low limit potentiometer Il with its tar i4 may be r, ed as one :set of four lees ot a Wineatstone bridge. The variable potentiometer I@ with its tee I3 and the hiel-1 tentiometer l2. with its teo l5; may. in a similar-mannen be viewed es another eet of four-.lees oi yanother Wheetstone bridge In`V the event the student pilot within the trainer l moves he eontro'ls oi the bank indicator beyond the il mit prescribed by the .Setting of thepotentiometer tap l5 on its Winding i2. then eleetromotiveioroe oi a voltage determined by the amount of lovertravel Will be transmitted through theliieh limit channel input transformeren.' amplied bythe series connected amplifier tubes?! and ,22 andimpressed upon the pair Qf-gridsof the discriminator tube 23. The

conductionof vthe discriminator tube 23 main-- tains a potential vmoon the grid of the thx/ration 2l and causes .it to maintain a direct Current eleotsromotive force through the upper half of the primary winding of a transformer 25 and the winding of a relay 26. The energization of the winding of the relay 26 opens the spring loaded normally elosed. Yrelay Contacts ily k2,3 rend 2e.v

Opening therelav Contact 2,9. stops e eloek rep-resented Aby the moter .3.3 and clutch :3.2 :in the timer Si.; @neninetlleeontaet l may stop a similar clock; not ,showni the simultaneous scoring circuit Slt-or aotilate such other device es may loe-desired.

When-the student pilot with-in the traner l returns the renti dieator 2 and the vpotentionieter I3 'beek Wi the permissible limits eetablislied by potentiometer' contact l5 on its winding I2. the de eribed electrical connections deee ereizeatlle relay Winding 25 and cause the sprineloaded relay contacts 2l. ,28 and 29 to again closet The closing of .the relay contact 29 again :impresses alternating current from a newer rSupply-5fore1tithe timer 3l and again starts the clock. The power supply preferably is common with the bridge power supply 5. Within the timer 3i the energization of the clutch 32 engages the clock motor 33. The alternating current power supply 5 supplies plate voltage to the discrimina-tor tubes 23 and 23 through the transformers 36 and 3l, respectively, and through the transformer 25 to the plates of the thyratrons 24 and 24.

In the described manner, each time the student pilot in the trainer I, by operation of the bank indicator 2, through its mechanical coupling 3, causes the potentiometer tap I3 to exceed the preestablished settings of the potentiometer taps I4 or I5 in the sensing bridge circuit, then an electrical output is passed through one or the other of the channel circuits and causes the clock in the timer 3i to be stopped. As a result a record is established on the clock in timer 3l, indicating the total time during which the student pilot has yremained within the permissible allowances in his manipulation of the bank indicator in the trainer I. Also a record is established in the simultaneous scoring circuit 30 indicating the total time during which the variables selected are maintained within the permissible limits simultaneously. For example, if it is desired to know the total time during which bank and pitch simultaneously were within limits, the simultaneous scoring circuit 30 and its associated timer would run only when both bank and pitch were within limits.

It will be noted that the high and low limit resistances each form a bridge circuit with the variable resistance and determine not only at which point but also in what phase the voltages in the bridges are developed.

With the high limit and the low limit resistances positioned on center as shown in the drawing, a movement of the contact I3 of the variable resistance beyond the high limit position as previously established, develops a voltage between the contact I3 of the variable resistance and 'the contact I5 of the high limit resistance. This voltage will be of an amplitude determined by the amount of over-travel and of a phase that is acceptable to the high limit channel.

When the variable contact I3 is moved in the opposite direction and below the low limit position, the amount of the Voltage developed is determined by the amount of over-travel, its phase is opposite to that developed on the high side and is acceptable to the low limit channel. The sensing bridge circuit may contain additional precision resistance potentiometers such as pitch, rate of turn, climb, air speed and the like, as desired.

Since the voltages applied to the potentiometers in the sensing bridge circuit are of alternating current, taking the high limit channel as an example, the instantaneous voltages are opposite at opposite ends of the high limit channel input transformer primary winding. These voltages are shifted 180 through the transformer 20 and are applied to a two stage amplier comprising the tubes 2I and 22 from which the amplified voltages are applied to the grids of the discriminator tube 23. If it be assumed that when the variable I3 is positioned within the set limits, the voltage applied to the grids of the discriminator tube 23 will be '180 out of phase with the voltage applied to the left anode of the tube 23 from the transformer 36. At the same time the voltage at the right anode of tube 23 supplied from the opposite end of transformer 36 will be in phase with the grid voltage. In this condition the right section only of tube 23 will conduct causing a voltage to be developed across the resistor 41, which is negative with respect to ground at the junction of resistors 46 and 41. This negative voltage applied to the control grid of the thyratron tube 24 is sufficient to prevent its ring. rIhis condition will exist in both channels as long as the Variable I3 in the sensing bridge circuit remains within specified limits between the low and the high limit potentiometer contacts I4 and I5. In the event the variable potentiometer contact I3 moves beyond the low limit established by tap I4 of low limit potentiometer II, the voltage applied to the input transformer 20 of the high limit channel is then changed in phase. The voltage applied to the low limit channel input transformer 20 however becomes of opposite phase from that which was previously applied. Under this circumstance the voltage at the grids of the discriminator tube 23 becomes in phase with the voltage applied to the left anode of tube 23. In this condition the left section only of tube 23 will conduct causing a voltage to be developed across the resistor 4l which is positive with respect to ground at thc junction of the resistors 41 and 46. This positive voltage applied to the control grid of the thyratron tube 24 is sufficient to fire the tube and to energize the relay 26 opening the contacts 2l, 28 and 29. Opening of contact 2l causes the scoring to be interrupted in the vsimultaneous scoring circuit. Opening of contact 23 stops the clock in timer SI. The contact 28 may operate additional devices where desired.

Each high and low limit channel consists of two stages of amplification, a discriminator stage and a thyratron. The channel input transformers 2i) and 23 have high impedance primary windings. The transformers 20 and 28 couple the signal from the sensing bridge circuit to the grids of the rst channel amplifiers 2I or 2l', respectively, each of which is a self-biased voltage amplifier stage.

In the high limit channel the secondary winding of the transformer 23 is connected to the grid of the amplier tube 2i through a resistor 4I). The voltage developed across a resistor 4I, which is the plate load resistor of the tube 2 I, is applied to the grid of the amplifier' tube 22 through a capacitor 42. The output from the second amplifier tube 22 is capacity coupled to both grids of the phase discriminator tube 23.

The alternating voltage developed across a resistor 43, which is the plate load resistor of the second amplifier tube 22, has been amplified illustratively 40G times so that a voltage of 1/100 volt applied to the grid of the rst amplifier tube 2| is now applied to the grids of the discriminator tube 23 as approximately 4 volts.

The plate or anode supply voltages for the discriminator tube 23 are illustratively 225 volts of 6D cycle alternating current and are obtained from the secondary winding of a transformer 36 and are out of phase. One cathode of the discriminator tube 23 is returned directly to ground and the other cathode is returned to ground through two resistors 46 and 4l connected in series and by-passed to ground through a capacitor 48. The junction of the resistors 46 and 41 is connected to the grid return resistor 49. The cathode end of the resistor 45 is coupled to the control grid of the thyratron 24 through a resistor 53. The firing point of theV thyratron 24 is controlled by an adjustable direct current volt- `plied to the cathode of the thyratron 24.

The first or left hand anode of the discriminator tube 23 is connected to the upper-most terminal or" the secondaryv winding of the transformer 36. When the Voltage applied to the iirst or left hand anode of the phase discriminator tube 23 from the uppermost terminal of the secondary winding of the transformer 36 is of positive polarity then the voltage applied to the second or right hand anode of the tube 23 from the lower-most contact of the secondary winding of the transformer 36 is of negative polarity.

Thevoltage supply for the anodes of the discriminator tube 23 and vfor the sensing bridge circuit which supplies the signal voltage to the grid of the first amplier 2l have a common source indicated as 5 and 5'. Connections are made in such a .manner that when the limit setting is exceeded in the sensing bridge circuit the voltage applied to the grid of the rst amplifier 2| and the voltage supplied to the rst anode of the discriminator tube 23 are both of positive polarity. When this condition exists, the upper half of the secondary winding of the transformer 36 conducts and a voltage is developed across the cathode resistor 46 of the tube 23. This voltage is pulsating direct current and is itered by the capacitor 48 which removes the A. C. component. The voltage developed across the resistor 46 is positive at the cathode end of the resistor and this voltage is applied through the resistor 5t to the control grid oi the thyratron 24. The resistor 56 is used as a limiting resistor and prevents the control grid of the thyratron 24 from drawing excessive current.

If the voltage applied to the two grids of the discriminator tube 23 is slightly out of phase with the voltage of the iirst anode of this tube, the right hand or second section of the tube 23 that has its anode connected to the lower-most contact or the secondary winding of the transformer 36, will conduct to some slight extent. When this occurs a voltage is developed across the cathode resistor 41. This voltage across the cathode resistor 41 is ofrpositive polarity at the ground end and is of negative polarity at the.

junction of the resistors 46 and 41. Since a voltage of negative polarity is already'present at the junction of the resistors 46 and 41 due to the voltage developed across the resistor 46, these negative voltages are additive and hence the positive voltage `at the cathode end of the resistor 46 becomes less positive by the amount of voltage developed across the cathode resistor 41. This reduction in positive voltage at the cathode end of the resistor 46 is not sufficient to prevent the ring of the thyratron 24. When the first or left hand side of the discriminator tube 23 is not conductingyhowever or when there is zero input such as is obtained at the balance point of the bridge in the sensing bridge circuit, the voltage developed across the cathode resistor 41 will be of suiiicient magnitude to cause the cathode end of the resistor 46 to be negative to such an extent as to prevent the nring of the thyratron tube 24.

A positive voltage applied to the cathode of the thyratron tube 24 through a thyratron bias potentiometer 55 and movable contact 56 may amount illustratively to approximately 14 volts direct current. This voltage acts as a stabilizing voltage to prevent the erratic ring of the thyratron 24 and the consequent chattering of the relay 26. When a positive voltage, obtained from the cathode of the discriminator tube 23, is aplelectric timer 3 I.

6 plied to the control grid of the thyratron 24`it causes the thyratron 24 to conduct The center vtap on the secondary winding of the` thyratron transformer 25 is connected through the `coiloi the relay 26 to ground, thereby completing the thyratron tube circuit. The liring of the thyratron tube 24 energizes the relay 26 to stop the The accuracy and the stability ofthe scoring system that is disclosed herein is yduel to a large extent to the operational characteristics of the discriminator circuit. The design of this circuit is such that the effect of stray pick up, slight phase differences or out of phase voltages, such as are developed when the student pilot within the trainer I isvremaining within limits, are controlled by the discriminator circuit so as to avoid the accidental firing of the thyratron 24. lThe discriminator circuit discriminates against unwanted frequencies and unwanted phase, and reduces noise and quadrature susceptibility.

The functions of the discriminator tubes 23 and 23 are substantially identical for both the high limit and the low limit channels. The discriminator insures clean, positive action of the amplifier since any minor changes in voltage or phasing could only tend to intensify the discrimi- "nator action.

When the bridge within the sensing bridge circuit is operating within limits, with the potentiometer contact I3 between the potentiometer contacts I 4 and I5, the voltage applied to the rst or left hand anode of the discriminator tube 23 is out of phase with the voltage applied to the grid of the tube 23 and consequently the rst or left hand side of the tube will not conduct. The polarity of the voltage applied to the second or right hand anode of the discriminator tube 23 however is such that the second section of the tube 23 will conduct. When this occurs, a voltage is developed across the resistor 41 which is positive at its grounded end and negative at the junction of the resistors 46 and 41. The voltage at the cathode end of the resistor 4E becomes negative by the amount developed across the resistor 41 since the section of the tube 23 using the resistor46 is not conducting and its voltage is zero. The negative'voltage at thefcathode end of the resistor 46 is applied through a resistor 56 vto the control 'grid of thev thyratron and is through one of the limit settings of the potentiometer arms I4 or I5, a point is reached where the voltage developed between the left end of the variable potentiometer resistor I0 and the potentiometer arm` or contact I4 or between the right hand end of the variable potentiometel'resistor I0 and the potentiometer tap I5, depending upon whether the variable arm i3 is at the left or right limit, is substantially zero. In common with all amplifiers, the scoring amplifier is subject to pick up, at this point.

With the voltage developed between the right hand end of the variable potentiometer resistor I0 and the high limit tap I5 zero, undesirable line harmonics, such as those caused by switches, motors and the like, may be applied to the high limit channel transformer 20 and, after amplication, to the pair of grids in the discriminator tube 23. These high frequency undesirable harmonies will cause both sections of the discriminator tube 23 to conduct equal amounts of electricity and the cathode end of the resistor 46 and the cathode end of the resistor 41 will each become positive by an equal amount. Since the lower end of the cathode resistor-41 is grounded and the cathode end of the resistor 45 is con,- nected through resistor 50 to the control grid of the thyratron 24, the Voltage developed between the control grid of the thyratron 24 and ground will be zero and will have no effect on the thyra.- tron 24. Thus the scoring amplier is not subject to failure because of the pick up, due entirely to the action of the double discriminator circuit.

The thyratron bias potentiometer 55 with its movable contact 56 is in the plate circuit of the scoring ampliers 2|, 22, 2l and 2,2', as shown. This potentiometer 55, 5B controls the amplitude of the positive voltage app-lied to the cathodes of the thyratrons 24 and 24. As the thyratron cathode is made more positive the grid becomes more negative and a point can be reached Where the thyratrons 24 and 24 will not fire when limits are exceeded. On the other hand with insufflcient bias the thyratrons 24 and 24 will fire continuously. A correct bias setting will be found to be when the potentiometer 55, 5B is set Within the center 30 of the total potentiometer angular displacement and when the scoring relay 26 will operate Without chattering when the limits are exceeded. Due to the amplitude of the positive voltage applied to the grids oi` the thyratrons 24 and 24 when limits are exceeded, this control has no eiect on the limits and Will not cause delayed firing of the thyratrons 24 and 24 or change the sensitivity of the system.

The disclosed scoring system records the time during which any group of devices illustrated herein by the bank indicator 2 in the trainer Il, is simultaneously held within its prescribed limits. Provision is made by the plurality of relay contacts 21, 28, 29 etc., for both simultaneous and separate scoring.

It is to be understood that the circuit and its components that are shown and described herein and its application to a representative device in an aircraft pilot trainer have been submitted for the purposes of illustrating and describing an operative embodiment of the present invention and that similarly functioning circuitry, components and applications may be made Without departing from the scope of the present invention.

What I claim is:

1. A scoring system, comprising a sensing bridge circuit containing a variable potentiometer and an adjustable limit setting potentiometer connected as a Wheatstone bridge to produce an error voltage when the movement of the variable potentiometer exceeds the adjustment of the limit setting potentiometer, an amplifier discriminator circuit converting the error voltage from said sensing bridge circuit into a direct current and containing a discriminator tube having a cathode electrode, thyratron means in said discriminator circuit having a control grid biased by the Vcathode of 'said disermineter tube, relay means energized by the direct current from the amplifier diecrimnater Circuit te open a relay contact, and a recording circuit energized upon an opening ofY the relay contact of said relay means.:

2, A scoring system, comprising a sensing .bridge circuit containing a variable potentiometer yand-a plurality of adjustable limit setting potentiorneters connected to produce an error voltage whenthe movement of the variable potentiometer exceeds the adjustment of one of the limit setting potentiometers, an amplifier discriminator circuit containing a plurality of channels corresponding to the plurality of adjustable limit setting notentiemeters in said sensing bridge circuit and converting the error voltage from said sensing bridge circuit into a direct current that is sustained during the time the movement o f the variable potentiometer exceeds the .setting of the limit setting potentiometer, a relay means en,- ergized by the direct current from the amplifier discriminator circuit to open a relay contact, and a timer circuit normally running a clock and deenergized t0 stop the clock during the time the variable potentiometer setting exceeds the adjustment of one of the limit setting potentiometers.

3. A scoring system, comprising a sensing bridge circuit containing a variable potentiometer and high limit and low limit adjustable limit setting potentiometers connected to produce an error voltage when the movement of the variable potentiometer exceeds the adjustment of one of the limit setting potentiometers, an alternating current source supplying electric energy to said sensing bridge circuit, a high limit channel containing a rst amplifier inductively coupled with said sensing bridge circuit and containing a rst phase discriminator and a first thyratron, a low limit channel containing a second amplifier inductively coupled with said sensing bridge circuit and containing a second phase discriminate/r and a second thyratron and said channel components powered from the alternating current Supplying electrical energy to said sensing bridge circuit, and relay means selectively energized by the ring of said rst or said second thyratron to open a plurality of relay contacts, a timer means stopped by the opening of a rst of said relay contacts.

WILLIAM W. WOOD, JR.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,694,237 Simonds Dec. 4, 1928 1,921,172 Taylor Aug. 8, 1933 2,357,745 Klievei Sept. 5, 1944 2,414,467 Hunt Jan. 21, 1947 

